The latest: The New York Times reports that Facebook is paying $2.8 billion in cash for Instagram.
This follows the $2 billion it paid for WhatsApp earlier this year.
A New York law firm has filed a lawsuit against Facebook, alleging that the social media giant misled users about its relationship with Instagram and WhatsApp, and that the company failed to properly disclose the deal.
Facebook, which has had a rough few years, has been fighting to get back into the business of selling ads on the social network.
In March, the social platform announced that it would start advertising on Instagram and other platforms, as part of a new partnership with Google.
Facebook said it had paid $100 million for ads on Instagram.
It has also been using the Instagram deal to increase its reach and get more people using the social networking site.
The company has also begun working with other tech companies, including Microsoft and Google, on a mobile advertising platform that will let advertisers target users on their phones.
The Times report says Facebook will use Instagram as part “of a new mobile advertising system” it is developing with the Google-owned company AdSense.
Facebook also announced in March that it was launching its own ads service on Instagram that will cost $1 a month for new users.